Method for controlling Sphaerotheca pannosa infections of rose plants using wax esters

ABSTRACT

A new method of preventing and eradicating  Sphaerotheca pannossa  (powdery mildew) infections on rose plants using a wax ester emulsion is provided wherein the wax esters emulsion is comprised of wax esters, which are derived from esterification of monoethylenic acids and monoethylenic alcohols having between 18 and 24 carbons, and a surfactant at a concentration of between 1% v/v and 7%v/v of the total wax ester component.

FIELD OF THE INVENTION

This invention relates to a method of controlling Sphaerotheca pannossa(powdery mildew) infection of rose plant by the application of afungicidal wax ester emulsion, wherein the wax esters are theesterification product of monoethylenic acids and monoethylenic alcoholshaving between 18 to 24 carbons each and are emulsified in water withsurfactants. Preferably, the wax esters are comprised of a mixture ofwax esters which are at least 85% identical to the type andconcentration of wax ester found in naturally occurring jojoba extract,with a surfactant at a concentration between 1% v/v and 10% v/v of thetotal wax ester mixture.

BACKGROUND OF THE INVENTION

Over the last thirty years it has been a goal of various governmentagencies to develop uses for the desert plant jojoba (Simmondsiachinensis), especially the extract produced from the jojoba seeds. Dueto the jojoba plant's ability to thrive in arid climatic conditions incoarse desert soils and it's life span which can extend up to 200 years,the plant was thought to be particularly useful for developing anagricultural industry in the underutilized lands of the Americansouthwest.

The jojoba plant produces an abundance of seeds with an average yieldfor a mature plant of about 12 pounds (dry weight). Jojoba seeds containabout 50% by weight of a colorless, odorless oily extract which iscommonly referred to as “jojoba oil”. The extract is chemically anunsaturated wax made up of non-glyceride esters having a narrow range ofchemical composition. Another natural source for wax esters isspermaceti, a wax produced from the head of the sperm whale. As thesperm whale is an endangered species and interstate sale of its oil wasbanned in 1973, it is not recognized as a particularly useful source forthese wax esters.

Jojoba oil is more than 97% wax esters. Each wax ester is derived fromone molecule of a long-chain monoethylenic alcohol esterified with onelong-chain monoethylenic fatty acid. The wax esters typically arecomprised of carbon chains of 38 to 44 carbon atoms. Suprisingly, thewax ester components of jojoba oil have been found to exhibit superiorfungicidal capabilities.

Powdery mildew is the common name applied to one of the most damagingand wide spread diseases in the agricultural and horticultural industry.Powdery mildew is a disease caused by species of several genera offungus on a number of different host plants. The variety ofhorticultural and agricultural plants susceptible to powdery mildewdisease is large. The disease is called “powdery mildew” because ofappearance of the mycelial growth gives a powder like appearance on thesurface of the host. The white powdery growth appears on infectedleaves, stems, fruit and flower buds. Infected leaves may also appeardistorted and fall from the plant. Powdery mildew spores are easilyspread by wind to nearby plant tissue and to other plants, resulting inan epidemic if left unchecked.

Sphaerotheca pannossa is the fungus species which causes powdery mildewinfection on rose plants. Powdery mildew infection is prevelent problemin the rose crop industry. This is particularly problematic since thiscrop value depends on its appearance. In fact, Sphaerotheca pannossainfection is known to cause millions of dollars in rose crop damage perannum.

Various chemical compounds have been disclosed which claim suitabilityfor use as a fungicide for controlling powdery mildew infection. Forexample, U.S. Pat. No. 5,366,995 discloses the use of short chain fattyacids and their salts as a fungicidal agent. The disclosed fatty acidsgenerally have carbon chains of between 7 to 20 carbon atoms andpreferably at 18 carbons. None of these application disclose the highmolecular weight wax esters commonly found in jojoba extract for use asa fungicidal agent. Further, jojoba extract has been reported as apretreatment to prevent powdery mildew infection on grape plants(Canadian Patent Application No. 2,103,014). In contrast, the subjectinvention is directed towards the use of wax esters for prevention anderadication of Sphaerotheca pannossa infection of rose plants.

In our studies, it has been surprisingly determined that the wax estersfound in jojoba extract are both an inert physical barrier and aneradicant of Sphaerotheca pannossa. This discovery gives rise tocommercially important applications.

In modern agriculture and horticulture the avoidance of unnecessaryenvironmental loading is a key commercial advantage. Both horticultureoils and fungicides are applied repeatedly during the early stages ofthe growing season to prevent the powdery mildew infection from becomingestablished. The oils and fungicides are applied multiple times pergrowth cycle to prevent powdery mildew infection and then again ifpowdery mildew appears. Since many crops have two or more growing cyclesper year, this leads to yet more fungicidal treatments. As a result, thefrequent fungicidal applications lead to a build up of that particularchemical agent in the environment (environmental loading).

Conversely, application of the wax esters of the subject invention canbe limited to instances where a powdery mildew infection occurs. Thus,wax ester fungicidal treatments are limited to a few, if any,application per growing season and environmental loading issignificantly lowered. Less fungicidal applications also results in alower cost to growers. In addition, the wax ester fungicidal agent israinfast after the application has dried. Thus, the wax ester fungicidalagent can prevent Sphaerotheca pannossa from infecting a rose plant in asingle application but also kills existing infections and then preventsreinfection over time. Jojoba extract has the ability to eradicateSphaerotheca pannossa tolerant or resistant strains that have evolvedunder current fungicidal protocols. Therefore, use of a jojoba extractas a fungicide is economically efficient and significantly reducesenvironmental loading.

The wax esters provide a greater degree of safety than horticulturaloils and fungicides. Many of the existing horticultural oils andfungicides are generally not environmentally safe in their application.For example, use of petroleum oils and sulfuric fungicidal applicationsfor powdery mildew are restrained under the federal regulations as theyhave serious environmental ramifications if applied in a concentratedform or in high volume. Further, the fungicides and oils are generallyvolatile. Thus, use of these materials is hazardous to workers applyingthe chemical. Another popular fungicide, sterol inhibitors, are alsoheavily regulated because of their environmental impact and the residuesthey leave on edible crops. The wax esters used in this inventionprovide particular stability and are significantly less volatile thanhorticultural oils. Specifically, the greater degree of unsaturation andthe long carbon chains, which are almost twice as long as fatty acidoils, enhances stability and non-volatility. Jojoba extract is a safeand natural application and is not heavily impacted by regulatory laws.

Additionally the wax esters of the subject invention have otheradvantages which make them a particularly effective as a fungicidalagent for treatment of Sphaerotheca pannossa infection in rose plants.For example, the long chained wax esters are generally non-toxic forpredator, beneficials and honeybees. The wax ester agent is generallynon-phytotoxic at the preferred range of use and, unlike many of theprior art fungicides mentioned above, never “burn” plant tissue. In factthe wax esters have been found to promote photosynthesis and stomatalconductance in the host plant.

SUMMARY OF THE INVENTION

It has been discovered that wax esters having high molecular weight area particularly effective and safe fungicidal application for preventingand eradicating Sphaerotheca pannossa infections on rose plants. Thisinvention provides a method for treating rose plants infected withpowdery mildew fungus with an emulsion of wax esters comprising waxesters of between 36 to 44 carbon atoms and a surfactant. The wax estersare derived from the esterification of monoethylenic acids andmonoethylenic alcohols having between 18 and 24 carbons and thesurfactant at a concentration of between 1% v/v and 10%v/v of the totalwax esters composition.

Thus, in a preferred embodiment the invention provides a method ofpreventing and eradicating Sphaerotheca pannossa infection on a roseplant wherein the method comprises spraying an aqueous emulsion of a waxesters with a surfactant onto the rose plant in an amount sufficient toreduce fungal infection in sprayed plants by at least 10% when comparedto plants not sprayed with wax esters and wherein at least 50% of thewax ester is comprised of carbon chains of 36 to 44 carbons atoms.

In another preferred embodiment of the present invention, the wax estersare derived from the esterification of monoethylenic acids andmonoethylenic alcohols. The monoethylenic acids are chosen from a rangeof 18 to 22 length carbon chains and the monoethylenic alcohols from arange of 20 to 24 length carbon chains.

In another preferred embodiment of the present invention, 50% to 90% ofthe wax esters are a mixture of eicosenyl eicosenoate and docosenyleicosenoate.

In yet another preferred embodiment of the present invention, the waxesters are comprised of a mixture of wax esters which are 85% similar intype and concentration to the wax ester found in naturally occurringjojoba extract.

In yet another preferred embodiment of the present invention thefungicidal agent is jojoba extract in an aqueous emulsion, with asuitable surfactant.

DEFINITIONS

The term “emulsion,” as used herein refers to a stable mixture of two ormore immiscible liquids held in liquid suspension. The mixture may bestabilized by the presence of emulsifiers or surfactants.

The term “aqueous emulsion,” as used herein refers to preparations of awax or oil distributed in small globules throughout the body of a secondliquid which is water. When the dispersed liquid is an oil or wax and isin the discontinuous phase and the dispersion medium is in thecontinuous phase it is an oil in water emulsion, whereas when water oraqueous solution is the dispersed phase and oil, wax or is thecontinuous phase, it is known as a water in oil emulsion.

The term “surfactants,” as used herein refers to emulsifiers,detergents, surface active agents, anti-foaming agents or compoundswhich reduce surface tension when dissolved in water of a watersolution, or which reduce interfacial tensions between two liquids. Thusthe surfactant changes the properties of a solvent so that immiscibleliquids may be more easily stabilized. Fundamentally, a surfactant is asingle molecule comprised of two structurally dissimilar groups ofopposing solubility tendencies, one which has an affinity for the phaseand the other which is antipathic to the medium. The surfactant causesadsorption at the solution's interfaces, orientates the adsorpedsurfactant ions or molecules , promotes micelle formation in the bulk ofthe solution, and orientates the surfactant ions or molecules in themicelle, thereby increasing the solubility of the solvent andstabilizing the mixture.

The term “wax esters,” as used herein refers to esters of long chain,even-numbered fatty acids and monohydric, straight chain, aliphaticalcohols, or sterols. Waxes are usually ester mixtures often accompaniedby small percentages of free fatty acids or high molecular weightunbranched hydrocarbons. The wax acids and wax alcohols usually have asimilar number of carbon atoms and are very hydrophobic.

The term “monoethylenic acids,” as referred herein refers to carboxylicacid organic compounds where the carboxyl group is attached to one endof a hydrocarbon and the hydrocarbon contains a single double bond.

The term “monoethylenic alcohols,” as referred herein refers to organiccompounds where one or more hydroxyl groups (OH) are present in ahydrocarbon molecule with no more than one hydroxyl group attached to asingle carbon atom and which also includes a single double bond in thehydrocarbon molecule.

The term “non-ionic surfactants,” as referred to herein refers tosurfactants, detergents or emulsifiers which do not ionize in water andthus are not subject to hydrolysis by aqueous solutions of acid oralkali.

The term “siloxanes,” as referred to herein refers to straight chaincompounds consisting of silicon atoms single-bonded to oxygen andarranged so that each silicon atom is linked with four oxygen atoms. Insome cases, hydrogen may replace two or more of the oxygens.

The term “polysiloxanes,” as referred herein refers to siloxane chainswherein some of the oxygens are replaced with organic substituents sothat a linear polymer results.

DETAILED DESCRIPTION

Introduction

Fungicidal infection in the rose crop industry represents a significantloss for rose growers in that fungal growth on crops may inhibitproduction of foliage and lower the lower overall quality of cultivatedroses. Sphaerotheca pannossa infection of rose plants is one of the mostcommonplace and damaging of such fungus. Current treatments forSphaerotheca pannossa have damaging environmental side effects, are notparticularly effective and in some cases are damaging to the rose plantitself.

It has recently been found that long chain wax esters have specialutility as a fungicidal agent for Sphaerotheca pannossa infection onrose plants. Particularly, aqueous emulsions of wax esters with asuitable surfactant, wherein the wax esters are the esterificationproduct of monoethylenic acids of between 18 and 22 carbon chains andmonoethylenic alcohols of between 20 to 24 carbon chains, are useful asfungicidal agent for Sphaerotheca pannossa infection on rose plants Thisinvention provides methods of use for wax esters as a fungicidal agentsfor the treatment and prevention of powdery mildew infection on roseplants.

Wax Ester Sources

The wax esters of this invention are most conveniently extracted fromSimmondsia chinensis (Jojoba). S. Chinensis is grown commercially forits wax esters. However, this invention is not intended to be limited bythe origin of the wax esters of either synthetically or biologicallyorigin. Sexual crosses between species is the genus. Related species inthe genus are expected to yield novel plants which produce the waxesters for use in this invention.

Jojoba extract is more than 97% wax esters. Wax esters are derived fromone molecule of a long-chain alcohol esterified with one long-chainfatty acid. Jojoba oil contains no glycerides, very little (1 percent)free acid or alcohol, and almost no hydrocarbons, steroids or othercontaminants. Carbon chains of 18 and 24 atoms long make up about 93% ofthe acids and alcohols in the wax esters.

The unsaturated acid components of jojoba's wax esters are mostly amixture of eicosanoic (C₂₀), docosanoic (C₂₂) and octadecanoic (C₁₈)acids. The unsaturated alcohols are a mixture of eicosanol anddocosanol, with smaller quantities of tetracosanol (C₂₄) and alcohols oflower molecular weight. Over 85% of the esters present in jojoba oil arecombinations of C₂₀ and C₂₂ acids and alcohols. The double bond positionon the acids and alcohols typically falls between carbon 11 and carbon12, and between carbon 13 and carbon 14.

More accurately, the alcohol content is comprised of 43.8%Eicos-11-enol, 44.9% Docos-13 enol and 8.9% Tetracos-15-enol (C₂₄). Theacid content consists of 71.3% Eicos-11-enoic acid, 13.6% Docos-13-enoicacid and 10.1% Octdec-9-enoic acid. Percentage's of compositioncomponents at or below 2% are defined as trace components and are notincluded in this description.

Further, the wax esters present in jojoba oil typically break down to30.9% Eicosenyl Eicosenoate (C₄₀), 43.2% Docosenyl Eicosenoate (C₄₂),7.6% Eicosenyl Docosenoate (C₄₂), 6.2% Tetracosenyl Eicosenoate (C44)and 5.9% Eicosenyl Octadecenoate (C₃₈). Percentage's of components below2% were defined as trace components and not included in the abovedescription.

Extraction of Wax Esters from Natural Sources

The extraction of wax esters from jojoba can be carried out by anystandard technique as is used in the industry for the extraction of fatsor waxes from seeds, beans or nuts. For example, crushing or pressingthe seeds and collecting the wax is one such technique. Other techniquescontemplated may be the use of solvents to extract the wax. Solventssuch as benzene, hexane, heptane and carbon tetrachloride have beenshown to readily extract the desired wax esters in a satisfactory yieldwithout special difficulty or affecting properties of the wax.esters.

Synthesis of Wax Esters

Although it is preferable to extract the wax esters for the subjectinvention from naturally occurring sources such as jojoba plant, waxesters of this invention can be synthesized by a variety of standardesterification methods as is known in the art (see March, J., “AdvancedOrganic Chemistry—Reactions, Mechanisms, and Structures”, 4^(th) ed.,(1992)). For example, an acid catalyzed esterification of carboxylicacids with alcohols ( the Fischer esterification reaction), whereinequilibrium is driven to the right, is one such esterificationtechnique. Techniques commonly used to drive this reaction to the rightinclude adding an excess of reactant (usually the alcohol), removal ofthe ester or water product by distillation, or removal of the waterproduct by azeotropic distillation, use of a dehydrating agent or amolecular sieve. One skilled in the art would appreciate that this isjust one of several esterification reactions available to the synthesizethe wax esters contemplated in this invention.

As described above, the esterification reactions would be carried outwith monoethylenic acid and alcohol precursors comprising carbon chainsfrom about 18 to 24 carbon atoms, which are commonly sold by a varietyof vendors. For the purposes of illustration, purchasing 13-docosaenoicacid and 11-eicosenol from Sigma-Aldrich Fine Chemicals Co. (see SigmaCatalog for Biochemicals and Reagents for Life Sciences, pg. 417 and 407respectively, (1999)), combining these two precursors with an acidcatalyst such as H₂SO₄ or TsOH while drawing off the product ester orwater by distillation would give the wax ester docosenol eicosenoate, awax ester whose use as a fungicidal agent is detailed in this invention.

Application of Wax Ester Fungicidal Agents

The wax ester fungicidal agent may be applied to a variety of roseplants including bushes, vines, miniatures or hybrids. Specifically, thesubject invention is contemplated to be used on any rose plant of thegenus Rosa. For example, the subject wax ester fungicidal agent isparticularly well suited for preventing or eradicating Sphaerothecapannossa (powdery mildew) infections for florabunda, grandiflora, hybridtea, miniature or bush rose species. More particularly, the subject waxester fungicide is an effective preventative and eradicant ofSphaerotheca pannossa var. rosa. One skilled in the art will appreciatethe vast number of rose plant species and varieties which exist and thatefforts to breed new species and varieties are currently underway. Thus,other species of rose plants which may be treated by the subjectinvention would be obvious to any person skilled in the art.

The wax ester fungicidal agent of this invention may be formulated intovarious forms such as solution, wettable powder, emulsion or spray, bymixing with any suitable solid or carrier such as water. It is preferredthat the wax ester application is applied in the form of an aqueousemulsion and such emulsions may also comprise a surfactant orcombination of surfactants.

The wax ester formulation may be applied by any of the methods typicallyknown and used in the agricultural industry for the application of achemical. Preferably, the wax ester composition would be applied by anycommon spraying technique, including crop dusting by airplane orvehicle. However, the most preferable method for application of thesubject wax ester fungicidal agent is by any ground or hand sprayerwhich is commonly used in the agricultural industry. The wax esteremulsion is sprayed over the entire plant just to the point of runoff.Alternatively, specific points of infection may be treated directlywithout effecting other parts of the rose plant. That is, a single bunchof leaves or flowers on a rose plant may be sprayed with care given notto apply the wax ester emulsion over the whole of the plant.

The surfactants which can be employed in the wax ester fungicidal agentcan be any of the non-phytotoxic surfactants which are customarily usedin preparing agricultural formulations. The surfactant would be onewhich adequately increases the solubility of the wax ester in water andwhich stabilizes the mixture by increasing break time so that the waxester emulsion stays in the emulsified state long enough to be appliedover a large acreage. Further, a surfactant should be chosen whichincrease the spreadability of the wax ester composition, so that the waxester solution spreads at the same rate as the water phase over thevarious treated surface. In this way a filmy, uniform and rainfastapplication of the wax esters is achieved. Specifically, it is preferredfor the present invention that the wax esters be mixed with a non-ionicsurfactant, a siloxane or a polysiloxane. Surprisingly, it was foundthat the optimal composition was one where the wax esters were mixedwith a non-ionic detergent to increase solution stability and then witha polysiloxane to enhance spreadability. Thus, the most preferredcomposition is one in which a combination of surfactants are employed.These type of surfactants and their use are well known in the art. Apreferable non-ionizable surfactant would be IGEPALCO[nonylphenoxypoly(ethyleneoxy)ethanol] or IGEPALCA[octyphenoxypoly(ethyleneoxy)ethanol], manufactured by Rhone-Poulenc.Additionally, a preferable polysiloxane surfactants would be apolyether-polymethylsiloxane-copolymer such as Break-Thru® OE 441, apolysiloxane manufactured by Goldschmidt Chemical Corporation.

The wax ester fungicidal agent of the present invention can be dilutedin order to facilitate its application in the field. Preferably, the waxester/ surfactant mixture would be diluted in water to form an aqueousemulsion and sprayed over the plant. The dilution should be at aconcentration to maximize fungicidal activities without injuring theplant. It is preferred that the wax ester /surfactant mixture be dilutedfrom 0.25% v/v to about 5% v/v in water for optimum fungus eradicatingand prevention activity. For example, a 0.25% to 0.5% emulsion would beproduced by mixing 1-2 pints of the wax ester/surfactant compositionwith approximately 40 to 50 gallons of water, for treatment ofapproximately one acre of the rose crop land. One skilled in the artwould appreciate that the stated volume of wax ester fungicide fortreatment of one acre represents an application for intermediatefoliage. The volume would be increased when the foliage of the treatedrose plants abundant and mature, and decreased when the foliage isrelatively sparse and new.

In addition to large scale applications for farms, greenhouse andagribusiness crop lands, the wax ester fungicidal agent can be employedas a preventative and eradicator of Sphaerotheca pannossa for home andgarden rose plants. Thus, it is contemplated that the wax ester agent isalso used in a ready-to-use formulation for home use. The preferredconcentrations of wax ester to surfactant to water is consistent as towhat has been described herein. Preferably, the ready-to-use formulationwould be 5% wax ester, 3.5% non-ionic surfactant and 3.5% siloxane orpolysiloxane surfactant, all of which is diluted in water to form an 12%wax ester/surfactant concentration in water. In addition, a non-dilutedwax ester/surfactant preparation of the same proportions above may beformulated as a refill product, where the refill product will later bediluted at the home by approximately 1 ounce of wax ester/surfactant to1 quart of water.

Those skilled in the art will appreciate that the time of application ofthe wax ester fungicidal agent is determined by the particularcharacteristics and environment of the rose species to be treated.Generally, the wax ester fungicidal agent can be applied at any time inthe growth cycle. Preferably, the wax esters are applied to the roseplant early in the growing season, most preferably on growth tips oryoung plant tissue, to prevent the infection from being established.This is particularly true where there has been prior infection in theprevious growing season since powdery mildew will overwinter insidestems and bud scales. Thus, application of the wax ester fungicide maybe made as early as just before the first buds swell. It is alsopreferable the wax esters are applied at the first sight of the powderymildew infection. In that way the infection may be eradicated before itspreads to other plants. Further, the wax ester residue is rainfast andwill coat the treated plant surface for some time, thus preventingreinfection.

The wax esters of the subject invention exhibit excellent fruit thinningabilities. Therefore, application of the wax ester composition as afungicidal agent is best made after anthesis. However, the subject waxester fungicidal agent may be applied at the flowering stage of the roseplant but greater care would have to be made to ensure that the waxesters are not applied to the fruiting body. Additionally, if a powderymildew infection exists at the time of harvest, application of the waxester fungicidal agent can still effectively be made.

Optionally, this invention is to be used at a time when ambienttemperature is not conducive to white fly infestation. White flyinfestation is associated with high heat and moisture, in a range from80° F. to 100° F., and most commonly between 85° F. to 95° F. Incontrast, powdery mildew is a disease associated with relatively cooltemperatures. Thus, the application of wax esters for control of powderymildew is made when temperature is below 80° F., and preferably between55° F. to 65° F. when powdery mildew first begins to appear.

While a single application of the wax ester fungicidal agent should besatisfactory for effective Sphaerotheca pannossa eradication, the waxester fungicidal agent may be applied multiple times to achieve thedesired effect. However, in applications wherein the wax estercomposition make up more than 2.5% of the aqueous solution by volume, asubsequent application cannot be applied for at least 10 days haveelapsed. or host injury may occur. Further, applications at or above 5%wax ester emulsion may result in an phytoxic effect on the leaves.

EXAMPLES

The following examples are offered to illustrate, but not to limit theclaimed invention.

Example 1 details a wax ester fruit thinning formulations.

Example 2 illustrates the fungicidal ability to eradicate and preventSphaerotheca pannossa infection on rose plants of aqueous emulsions waxesters.

Example 1

Example 1 provides a preparation of a wax ester and surfactantcomposition diluted water to form an aqueous emulsion for use as afungicidal agent. Specifically, herein is provided the preparation of acomposition of wax esters which resemble in type and concentration thewax esters found in jojoba extract by at least 85%, with a combinationof surfactants to increase stability and spreadability of the wax estersolution, in an aqueous emulsion.

A solution containing 93% v/v of a wax ester mixture comprising 43%docosenyl ecosenoate, 30% eicosenyl eicosenoate, 7.5% eicosenyleicosenoate, 6% tetracosenyl eicosenoate and 5% eicosenyl octadecenoate,with a 7% mixture of surfactants was prepared. The solution was preparedby mixing together 93% jojoba extract v/v with 3%v/v a non-ionic typesurfactant and 4% polysiloxane type surfactant. The non-ionic surfactantwas Igepal CA-520 from Rhone-Poulenc, which is an octylphenol ethoxylatecontaining 5 moles by weight of ethylene oxide. The polysiloxane usedwas Break-Thru® OE-441 from Goldschmidt Chemical Corporation, which is apolyether-polymethylsiloxane-copolymer. The wax ester and surfactantcomposition was mixed for 20 minutes by return flow agitation. Theresultant solution contained the wax esters at the desired stability andspreadability to effectively destroy powdery mildew fungus infectionover a rose plant surface. The wax ester solution can then be diluted inwater to form an aqueous emulsion for application to rose plant.

Example 2

Example 2 demonstrates an aqueous emulsion of wax esters application foreradicating Sphaerotheca pannossa (powdery mildew) infection on roseplants.

The wax ester fungicideal agent was prepared according to Example 1 atconcentrations of 0.5%, 1%, 2.5% and 5% (by volume) diluted in water.The wax ester emulsion was applied onto separate potted plants of theTyler variety, hybrid Tea rose plants. The effect of the wax esteremulsion was compared to untreated trees to establish the fungicidalcapability of the wax esters. The wax ester was applied by handsprayerto runoff over the whole of the rose plant. Three replications of theexperiment were completed.

Data was gathered at 6 days after the first application and the again 8days after all 4 treatments were applied. On those days, evaluationconsisted of rating plant tissue including foliage, flower buds, flowerstems and flowers for both the percentage incidence of fungal infectionover the plant and the severity of infection at those points ofinfection. Table 1 summarizes the percentage powdery mildew infectionreduction data for the unsaturated wax ester treatment versus untreatedplants.

TABLE 1 Average Powdery Mildew Infection (%) Pre-treatment 6 Days After1 App1n. 8 days after 4 App1ns. Formulation (% v/v) Incidence SeverityIncidence Severity Incidence Severity Untreated 25% 27% 28% 33% 26% 22%.5% Wax Ester 22% 23% 10% 10% 0.0% 0.0% 1% Wax Ester 25% 28% 10% 10%0.0% 0.0% 2.5% Wax Ester 22% 25% 13% 20% 0.0% 0.0% 5% Wax Ester 28% 25%17% 23% 0.0% 0.0%

It was found that a wax ester fungicidal agent applied in an aqueousemulsion effectively destroyed Sphaerotheca pannossa infections bothafter a single application and, to a greater extent, with multipleapplications. That is, a marked decrease in powdery mildew infection wasobserved after a single treatment and complete eradication was achievedafter 4 applications. Further, the plants did not exhibit a reinfectionof Sphaerotheca pannossa despite the presence of the infected butuntreated rose plants, which were still in close proximity to thetreated plants.

It is understood that the examples and embodiments described herein arefor illustrative purposes only and that various modifications or changesin light thereof will be suggested to persons skilled in the art and areto be included within the spirit and purview of this application andscope of the appended claims. All publications, patents, and patentapplications cited herein are hereby incorporated by reference in theirentirety for all purposes.

What is claimed is:
 1. A method for controlling an Sphaerotheca pannossainfection on a rose plant, said method comprising: spraying an aqueousemulsion of a wax ester, or mixture of wax esters, with a surfactantonto the growth tips of the rose plant, said emulsion in an amountsufficient to reduce fungal infection in the treated rose plants by atleast 10% of the amount in absence of said wax ester, wherein the waxester is derived from jojoba extract, wherein the weight ratio ofsurfactant to wax ester is from 1:10 to about 1:50 and wherein theemulsion is between about 0.25% to about 7% v/v wax esters andsurfactant.
 2. The method of claim 1 wherein the rose plant is a hybrid.3. The method of claim 1 wherein the rose plant is chosen fromgrandiflora, florabunda, bush, miniature or tea rose plants.
 4. Themethod of claim 1 wherein the emulsion further comprises a surfactant,or combination of surfactants selected from a group consisting of:ethoxylated alkyl phenyl ethers, siloxanes and polysiloxanes.
 5. Themethod of claim 1 wherein about 50% to about 90% of the wax ester is amixture of eicosenyl eicosenoate and docosenyl eicosenoate.